Setting tool length

I’ve only ever set tool length by touching off the actual part, but I need to get friendly with the ETS. I have a general question about theory.

If I touch all tools off on the ETS, can I simply touch off any tool on the top of the part to make zero and the other tools will all fall in line? Or do all tools then also need to be touched off the part even though they were touched off at the EST?


Yes, you can touch off one tool to the top of the part, as long as you have the correct offset selected.

Thank you,

Each tool has a specific length dictated by the Z position of you tool setter. These should populate the length column in the tool offset page. Once all tools are set off the ets you control the z0 position of all tools with the fixture offset G54, G55, G56, etc.

So, the relative height between the tool setter and part doesn’t matter as long as they were all set at that height under the G54. And when I zero the X,Y and Z the heights will all still be good relative to each other?

Yes. When setting Z you have to subtract the length of the tool you touched off with. So that the machine thinks you touched the spindle nose to the part. When you run the tool you will reinstate the tool length with G43 and an H plus tool number ex. G43 H3 for tool 3. This tell the machine to stop each individually called tool length from the top of the part.

Am I correct in my thinking? I’d like to have tools setup in my tool offset chart and use the different work location offsets.
I believe the best way is to set all the tools off the machine table using G54 as a baseline, keeping “0” in the Z location, set all my tools. Then I can input the height of my work pieces into the different work locations. I use several fixtures that require the same tool or different tools.
I will have to return to the G54 offset for any tool height settings, correct?

@Fred_Nies these two videos might help you understand tool and work offsets a little more. You are on the right track.